From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 90FEDC433EF for ; Fri, 20 May 2022 10:23:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346559AbiETKXF (ORCPT ); Fri, 20 May 2022 06:23:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45102 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346302AbiETKXE (ORCPT ); Fri, 20 May 2022 06:23:04 -0400 Received: from mail-ed1-x536.google.com (mail-ed1-x536.google.com [IPv6:2a00:1450:4864:20::536]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5ECA6E2776 for ; Fri, 20 May 2022 03:23:03 -0700 (PDT) Received: by mail-ed1-x536.google.com with SMTP id s3so10180898edr.9 for ; Fri, 20 May 2022 03:23:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:from:date:message-id:subject:to; bh=UqgoitLhyMN19YzP8hRzAqqQOEGPkVN4/V2PhW8+bOo=; b=bRdAUN6rJkGoDFmR6BRF/j9fmlwp1Wk51IrYNTbRpc0teqPSSIfThcJvKuGkgKljQ9 Xt9IC8dPFpNUD4s4v9Nv4Xirn6go6z3XmU03mhL6f+KR0Wam5P104PEWlwaLBoLjKH6q umJj/Rw5WUfgQgAn6Ug87X9vJ7TDEIx+isWI1QS4rAA8fpOdcuDoQiBR3GGYf3p2F723 1pPfmOD/H6QCCTm6rIAar+Q6t7ye6lUMQAetbt6dxmeaA2U7460qUUYxEYIz3RsS9Puu e5e9O1SUnEIaqTTqstYa7BOvilbCS8gJCUTh47kdr6vj5ATYuOzGOhm5jEclDnqBLKFB LdeQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=UqgoitLhyMN19YzP8hRzAqqQOEGPkVN4/V2PhW8+bOo=; b=kZycj0/q7TivP6cWkqyn2LLteBnUzF/EeMftLuzQAv+Zr5yOxKW9ECySWJ/szkFthM T5CrUyG70Sjb62wgRiL135sDveVpUehX9ytm662UCSbbXtl1+qsNJgoFaZbFfWg83DLO 52D5yXMxiHfVLxQtU555ZIMqioX8XgzM9LmM+9dqUi0Iwz3wo7fVGTj+bxMfMNd/q8l+ E3yznQ/isLkrYCZWhBd/jcJ+hRXmEmGnZjadO3gC9gKTLzSX/Oe36UjYECrPwyXymZhn 6vBpYQteqSczttcw1+g0ibq6IJlvidmeXEInG2SCzqcFqjy/+OJCQP2ucPYm4D/kbcCm xs2Q== X-Gm-Message-State: AOAM531MGmY5NhfrcPQ/tSTWN+2dOAPG6Q6vddDY4nX3fh7tBJfO0oD2 dsGeDgNd4PablOwBBoVCFefVXVyt1AWgZQS1x84K5YvarSs= X-Google-Smtp-Source: ABdhPJy8IUjW3UAN1X7k7p+Uy2RrJYxBgZgb+MztzBE6C1NqzBS+5XapsyfNsI4WeBgRHjPIlg5I3wBClWOaN4U75Rk= X-Received: by 2002:a05:6402:34d4:b0:42b:35e5:fc78 with SMTP id w20-20020a05640234d400b0042b35e5fc78mr395488edc.372.1653042181697; Fri, 20 May 2022 03:23:01 -0700 (PDT) MIME-Version: 1.0 From: Stefan Hoffmeister Date: Fri, 20 May 2022 12:22:50 +0200 Message-ID: Subject: Thunderbolt: One missing DisplayPort? To: linux-usb@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org I am trying to diagnose a problem where I get video output on Thunderbolt on one DisplayPort, but no output on the second DisplayPort. I would love to turn on all the (kernel-level) logging output that there is, but do not know how to do that. Basically, on a Dell Inspiron 16 Plus (7610) laptop with Thunderbolt 4, I am running Fedora Linux 36 with kernel 5.17+. Connecting that laptop to a Thunderbolt docking station (Intel Thunderbolt 3 chip inside), with two screens attached via DisplayPort, I get only one screen up and running. I'd like to discover more about this apparent error mode, because attaching a different TB3 setup works fine. I am looking for some means to enable logging or to get debugging insight. Generally speaking, I suspect that this specific Dell laptop (configuration) has some challenges in the BIOS, and with Thunderbolt in general, but am totally blind to what is going on. This system offers potential for fun, this being a hybrid PRIME configuration, with an Intel iGPU passing through to an Nvidia dGPU which seems to be the only wired-up way to get DisplayPort output.